Polishing pad wear detecting apparatus

ABSTRACT

A polishing pad wear detecting apparatus suitable for a chemical mechanical polishing (CMP) apparatus is provided. The polishing pad wear detecting apparatus includes an arm and a height detector. One end of the arm is fastened on the CMP apparatus. The height detector is disposed on the arm for detecting height variation of a polishing pad.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to a detecting apparatus of a chemical mechanical polishing (CMP) apparatus, and more particularly, to a polishing pad wear detecting apparatus.

2. Description of Related Art

Because the resolution of photolithography exposure increases along with the decrease in device size and the depth of field at exposure is reduced, the requirement to flatness of chip surface increases drastically. Thus, when performing the deep sub-micron process, the planarization of the chip then depends on the chemical mechanical polishing (CMP) process. The unique anisotropic polishing property of the CMP process is not only used for the planarization of the surface contour of the chip, but can also be applied in the fabrication of damascene structures of perpendicular and horizontal metal interconnections, the fabrication of shallow trench isolations in devices and the fabrication of advanced devices in the previous stage, and the fabrication of micro-electromechanical system planarization and the fabrication of flat displays, etc.

The CMP process mainly utilizes a reagent in the polishing slurry for generating a chemical reaction on the front side of the wafer to faun a polishable layer. Further, with the wafer on the polishing pad, the protruding portions of the polishable layer are polished off by the mechanical polishing with the facilitation of abrasive particles in the polishing slurry. The chemical reactions and the mechanical polishing are then repeated to form a planar surface.

The polishing pad in the CMP process is consumptive and will be worn off during the polishing process. When a specific product is polished, the number of wafers that can be polished by using a single polishing pad is set in advance, and a polishing pad is replaced once the preset number of wafers has been polished by using the polishing pad. However, such a polishing pad replacement rule cannot reflect the actual wear status of a polishing pad. If the polishing pad is already worn off and should not be used anymore before the number of wafers polished by using the polishing pad reaches the preset number, the polishing efficiency will be reduced if this polishing pad is still used for polishing more wafers. If the wear status of the polishing pad is not serious and the polishing pad can be further used after the polishing pad has been used for polishing the preset number of wafers, the consumptive material cost will be increased by replacing the polishing pad.

SUMMARY OF THE INVENTION

Accordingly, the invention is directed to a polishing pad wear detecting apparatus that can precisely detect the wear status of a polishing pad in real time.

The invention provides a polishing pad wear detecting apparatus adaptable to a chemical mechanical polishing (CMP) apparatus. The polishing pad wear detecting apparatus includes an arm and a height detector. One end of the arm is fastened on the CMP apparatus. The height detector is disposed on the arm for detecting the height variation of a polishing pad.

According to an embodiment of the invention, in the polishing pad wear detecting apparatus, the arm may be fastened on the CMP apparatus through pivoting to allow the arm to scan above the polishing pad.

According to an embodiment of the invention, in the polishing pad wear detecting apparatus, the length of the arm may allow the height detector to be located above a central spot of the polishing pad.

According to an embodiment of the invention, in the polishing pad wear detecting apparatus, the material of the arm may be a rigid material.

According to an embodiment of the invention, in the polishing pad wear detecting apparatus, the height detector may be a non-contact height detector or a contact height detector.

According to an embodiment of the invention, in the polishing pad wear detecting apparatus, the non-contact height detector may be an electromagnetic impedance detecting device, a laser transmitting and receiving device, or an ultrasound transmitting and receiving device.

According to an embodiment of the invention, in the polishing pad wear detecting apparatus, the contact height detector may be a stylus device.

As described above, in a polishing pad wear detecting apparatus provided by the invention, the height detector disposed on the arm can detect the height variation of a polishing pad in real time. Accordingly, the wear status of the polishing pad can be precisely detected in real time.

These and other exemplary embodiments, features, aspects, and advantages of the invention will be described and become more apparent from the detailed description of exemplary embodiments when read in conjunction with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a diagram illustrating how a chemical mechanical polishing (CMP) apparatus polishes a wafer according to an embodiment of the invention.

FIG. 2 is a side view of FIG. 1, wherein the wafer is not illustrated.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a diagram illustrating how a chemical mechanical polishing (CMP) apparatus polishes a wafer according to an embodiment of the invention. FIG. 2 is a side view of FIG. 1, wherein the wafer is not illustrated.

Referring to both FIG. 1 and FIG. 2, the polishing pad wear detecting apparatus 100 is adaptable to a CMP apparatus 200. In the present embodiment, a substrate being polished is a wafer W, for example. The CMP apparatus 200 includes a carrier 202 and a polishing pad 204. The polishing pad 204 is disposed on the carrier 202 and includes a polish area 206 and a non-polish area 208. The wafer W is placed within the polish area 206 of the polishing pad 204 to be polished. The part of the polishing pad 204 within the non-polish area 208 does not contact the wafer W, and therefore the part of the polishing pad 204 within the non-polish area 208 won't be worn off. In addition, the CMP apparatus 200 may further include other components, such as a rotating plate and a polishing slurry conveying pipe. Since these components are well known to those having ordinary knowledge in the art therefore are not illustrated in FIG. 1 and will not be described.

The polishing pad wear detecting apparatus 100 includes an arm 102 and a height detector 104. One end of the arm 102 is fastened on the CMP apparatus 200. The arm 102 may be fastened on the CMP apparatus 200 through pivoting to allow the arm 102 to scan above the polishing pad 204. For example, the arm 102 may be pivoted onto the carrier 202 of the CMP apparatus 200 by using a supporting shaft 106, but the invention is not limited thereto. The length of the arm 102 may allow the height detector 104 to be located above the central spot of the polishing pad 204. The central spot of the polishing pad 204 may be the non-polish area 208 of the polishing pad 204. The arm 102 may be made of a rigid material.

The height detector 104 is disposed on the arm 102 for detecting a height variation ΔH of the polishing pad 204. The height detector 104 may be a non-contact height detector or a contact height detector. Herein, the non-contact height detector may be an electromagnetic impedance detecting device, a laser transmitting and receiving device, or an ultrasound transmitting and receiving device, and the contact height detector may be a stylus device.

According to the embodiment described above, when the wafer W is polished by using the CMP apparatus 200, because the polishing pad 204 rotates along the direction D, the polish area 206 and the non-polish area 208 of the polishing pad 204 are scanned by using the height detector 104 disposed on the arm 102, and the height variation ΔH at each position on the polishing pad 204 is detected based on the height of the non-polish area 208 of the polishing pad 204. Thus, the wear status of the polishing pad 204 can be precisely detected in real time according to the height variation ΔH of the polishing pad 204 detected by the polishing pad wear detecting apparatus 100. Accordingly, the appropriate time for replacing the polishing pad 204 can be correctly determined.

In addition, the polishing pad wear detecting apparatus 100 can help to determine the appropriate time for replacing the polishing pad 204, so as to prevent the worn-out polishing pad 204 with low polishing efficiency from being still utilized for the polishing process, and to reduce the replacement cost by preventing any usable polishing pad 204 from being replaced untimely.

In summary, the polishing pad wear detecting apparatus in an embodiment of the invention has at least following features:

1. The polishing pad wear detecting apparatus can precisely detect the wear status of a polishing pad in real time;

2. The appropriate time for replacing a polishing pad can be determined by using the polishing pad wear detecting apparatus.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents. 

1. A polishing pad wear detecting apparatus, suitable for a chemical mechanical polishing (CMP) apparatus, the polishing pad wear detecting apparatus comprising: an arm, wherein one end of the arm is fastened on the CMP apparatus; and a height detector, disposed on the arm, for detecting a height variation of a polishing pad.
 2. The polishing pad wear detecting apparatus according to claim 1, wherein the arm is fastened on the CMP apparatus through pivoting to allow the arm to scan above the polishing pad.
 3. The polishing pad wear detecting apparatus according to claim 1, wherein a length of the arm allows the height detector to be located above a central spot of the polishing pad.
 4. The polishing pad wear detecting apparatus according to claim 1, wherein a material of the arm comprises a rigid material.
 5. The polishing pad wear detecting apparatus according to claim 1, wherein the height detector comprises a non-contact height detector or a contact height detector.
 6. The polishing pad wear detecting apparatus according to claim 5, wherein the non-contact height detector comprises an electromagnetic impedance detecting device, a laser transmitting and receiving device, or an ultrasound transmitting and receiving device.
 7. The polishing pad wear detecting apparatus according to claim 5, wherein the contact height detector comprises a stylus device. 